Thermus thermophilus Genome
Thermus thermophilus is a species of hyperthermophilic bacteria, capable of growing in temperatures up to 85 degrees Centigrade. The genome of T. thermophilus strain HB27 was sequenced and annotated in 2004 by Anke Henne and colleagues using shotgun sequencing (1 ). Phylogeny Based on the sequence of the 16S rRNA, the Thermus genus has been placed in the same phylum as the related Deinococcus bacteria. Though they are distantly related, the relation is distinct enough to group the two bacteria in the same phylum. T. thermphilus fits in this phylum, Deinococcus-Thermus, and is a member of the order Thermales. The Thermus genus is also related to other thermophiles, such as Thermotoga maritima, based on the G+C content of the rRNA sequences. This relationship is based mostly on the concept of thermostability of the sequences rather than evolutionary proximity (2 ,3 ,4 ). Overall Structure The genome of T. thermophilus consists of a chormosome and a megaplasmid. The chromosome is 1,894,877 base pairs and the plasmid (called pTT27) is 232,945 base pairs. The entire genome contains for a predicted 2,218 genes, of which 1,482 are putative protein-coding genes, based on annotations by the authors of the study. Other notable features are a G+C content of around 69.4% and 53 mobile DNA fragments, or insertion elements (1 ). Physiology After studying the genome of T. thermophilus, the researchers were able to determine some key features about the physiology of the species. Since neither flagella biosynthesis genes nor chemotaxis cascade genes were found in the genome, it was reasoned that the species is generally immobile and sticks to surfaces. This was reinforced by the finding of other scavenger genes, which whould indicate that the organism adheres to surfaces and picks up nutrients as they pass by. T. thermophilus contains genes necessary for growth on proteins or carbohydrates. The genes needed to synthesize all 20 amino acids are also present. Certain genes allowing for anaerobic growth, such as those for nitrate reductases, are absent in the genome of T. thermophilus ''HB27. This is reasonable because this strain is aerobic, unlike the closely related HB8 strain, which does have the genes necessary for these proteins associated with anaerobic growth (1 ). Biotechnological Promise After annotating the genome, it was apparent that there were two categories of genes present which would make ''T. thermophilus a biotechnologically useful organism. Of importance are those involved in the biosynthesis of vitamins (specifically vitamin B12, cobalamin) and those involved in carotenoid biosynthesis. This organism contains all of the genes needed to make cobalamin, an important vitamin for humans. T. thermophilus could be used to generate large quantities of this vitamin. Carotenoids are important in the food and pharmaceutical industries. Similar to cobalamin production, T. thermphilus could be utilized to synthesize large quantities of these important molecules (1 ). Biosynthetic genes are not the only ones that can be harnessed from this organism. As with many other thermophilic bacteria, T. thermophilus can produce many thermally stable proteins. These proteins include DNA and RNA processing enzymes, cabohydrate hydrolases, proteases, alcohol dehydrogenases, and phoshatases. All of these proteins, being thermally stable, could have many biotechnological applications. This is seen with the DNA polymerase of the related species Thermus aquaticus ''(1 ). One last feature worth mentioning is in regard to genetic manipulation. Unlike other ''Thermus species, T. thermophilus has the ability to be genetically engineered, which could be very useful in producing other thermally stable proteins or cofactors found in other thermohiles (1 ). References 1. [http://www.nature.com/nbt/journal/v22/n5/pdf/nbt956.pdf Henne, A, et al. The genome sequence of the extreme thermophile Thermus thermophilus. Nature Biotechnology. 2004.] 2. [http://www.ncbi.nlm.nih.gov/pubmed/11542160 Weisburg, WG, et al. The Deinococcus-Thermus phylum and the effect of the rRNA composition on phylogenetic tree construction. Syst Appl Microbiol. 1989.] 3. KEGG Organisms - Thermus thermophilus. 4. [http://en.wikipedia.org/wiki/Thermus_thermophilus Wikipedia - Thermus Thermophilus.]